COVID-19 has not only had a grave toll on the human population, but the race for a COVID-19 vaccine that will help save lives will also have a grave toll on an ancient marine organism, the horseshoe crab. For over 445 million years, the Limulus polyphemus, also known as the American horseshoe crab, has inhabited the waters along the shore of the eastern side of the United States. Every summer, horseshoe crabs come ashore to breed, leaving a vital supply of eggs for migratory shorebirds [1]. Horseshoe crabs play a crucial role in the ecosystem as a generalist who can feed on anything on the seafloor while at the same time playing a crucial role in the sustainability of our ecosystem, humanity. 

Horseshoe crabs have blue blood because their blood is copper-based instead of iron-based, iron being what makes our blood red. Their blood produces limulus amebocyte lysate, or LAL, which makes their blood coagulate much faster than human blood [2]. Pharmaceutical companies have unsustainably harvested horseshoe crabs and drained their blood for decades, using this blue blood to test vaccines for the presence of endotoxins or anything that could potentially harm a human. This blue blood is so precious that just a gallon of blood can cost up to $60,000 [1]. These crabs have been protecting the human race from harmful vaccinations since the 1970s. Humanity has horseshoe crab blood to thank for our global health in the face of harmful viruses and diseases.

The unsustainable harvesting of this blood for medical and commercial bait purposes has led to a decline in American horseshoe crab populations. When horseshoe crabs are harvested for medical purposes, they are drained of most of their blood and then returned to the ocean. The horseshoe crab is then weak and often left in an unfamiliar place, which leads many of these “used” horseshoe crabs to die in the wild. The horseshoe crab is currently listed as a “Near Threatened” species, but continued harvesting and destruction of habitats will hurt the horseshoe crab population even further [2].

In hopes of saving the horseshoe crab population, scientists have created a synthetic form of LAL called recombinant factor C, rFC. The use of the synthetic form instead of the horseshoe crab’s LAL  has been approved in Europe, but not in the US. Because of this, all COVID-19 vaccines, whether they are developed in the US or any other part of the world, will have to be tested using horseshoe crab’s LAL in order to be approved and distributed in the United States [1]. To account for the mass distribution of COVID-19 vaccines, more horseshoe crabs will likely be harvested to guarantee the safety of all injections. This creature that has survived 5 mass extinctions and has lived for more than 445 million years will now ensure the health and safety of our own human population and can hopefully be the light guiding us through to the end of the Coronavirus pandemic. Will it be able to survive, as well?

Written by Jen Wisnewski

References:

1. Arnold, C. (2020, July 02). Horseshoe crab blood is key to making a COVID-19 vaccine-but the ecosystem may suffer. Retrieved November 23, 2020, from https://www.nationalgeographic.com/animals/2020/07/covid-vaccine-needs-horseshoe-crab-blood/

2. CBS News. (2020, November 10). Horseshoe crabs help keep vaccines safe. Now, they're in big trouble. Retrieved November 23, 2020, from https://www.cbsnews.com/news/horseshoe-crabs-vaccines-extinction/